I have run several roots type blowers and I am wondering a few things about your project. First, why are you using the stock heads? If it is because of a tight budget I would put the project on hold until you can acquire some better heads. Secondly if you are running a 671 blower you should consider 2 carbs even if you run smaller cfm carbs because dual carbs will offer a MUCH better fuel distribution with a roots type blower. I also recommend that you talk with Comp Cams about a blower specific camshaft kit which will favor a little more lift on the exhaust side and they will recommend a cam that has been ground on a 114. Hope this helps.

A single Holley 800 will do fine if you're not looking to make any real power. As far as the cam, in my engine I used a NitrousHP cam from Comp, worked great. If your block is a 4-bolt, no point doing the splayed caps thing..waste of money on that stock block. Your heads are junk, look on Craigslist or Racingjunk or even here for a used set of aftermarket heads.

Later the same summer, a few days before the engine exploded, I went to another temporary track with just unprepared tarmac. I had just built a more free flowing exhaust and power increase was substancial.